Adjustable chair



FIG. 1 is a front and left side perspective view of an adjustable chair showing my new design;

FIG. 2 is a front and right side perspective view thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a rear view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof. 

CLAIM The ornamental design for an adjustable chair, as shown. 